/*
 * Copyright (c) 2004-2022, University of Oslo
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * Neither the name of the HISP project nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.hisp.dhis.system.util;

import java.io.Serializable;

/**
 * Optional for {@link Serializable} values. Accepts nulls.
 *
 * @author Lars Helge Overland
 */
public class SerializableOptional implements Serializable {
  private final Serializable value;

  private SerializableOptional() {
    this.value = null;
  }

  private SerializableOptional(Serializable value) {
    this.value = value;
  }

  /**
   * Creates a {@link SerializableOptional} with the given value.
   *
   * @param value the value.
   * @return a {@link SerializableOptional}.
   */
  public static SerializableOptional of(Serializable value) {
    return new SerializableOptional(value);
  }

  /**
   * Returns a {@link SerializableOptional} with a null value.
   *
   * @return a {@link SerializableOptional} with a null value.
   */
  public static SerializableOptional empty() {
    return new SerializableOptional();
  }

  /**
   * Indicates whether a value is present.
   *
   * @return true if a value is present.
   */
  public boolean isPresent() {
    return value != null;
  }

  /**
   * Returns the value, may be null.
   *
   * @return the value.
   */
  public Serializable get() {
    return value;
  }
}
